Carbon baking furnace with system for controlling movement of sacrificial medium and anodes through the baking path

ABSTRACT

A carbon baking furnace has at least one vertical baking shaft with a system and method for positioning green carbon bodies to be baked at the tops of the vertical baking paths and ringing the green carbon bodies with a sacrificial medium such as packing coke. The disclosure provides a carbon baking furnace having a system and method for unloading baked carbon bodies at the bottom of an array of baking paths while supporting the column of carbon bodies remaining in the baking path. The disclosure provides a volatile extraction system that extracts volatile fumes from the upper portion of the furnace and introduces the volatile fumes to the burners in the baking portion of the furnace. This system allows the volatile fumes to be selectively directed to an afterburner and automatically delivered to the afterburner during an emergency.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application61/714,634 filed Oct. 16, 2012; the disclosures of which areincorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

1. Technical Field

The present disclosure generally relates to carbon baking furnaces and,more particularly, to carbon baking furnaces having vertically-disposedbaking paths. In one configuration, the invention relates to a furnacehaving at least one vertically-disposed baking path used to bake acarbon body that travels down through the baking path while packed in asacrificial medium.

2. Background Information

Various operations require green carbon to be baked prior to use. Someof these operations use granulated green carbon while others use blocksof green carbon. One such baking operation is the manufacture of anodesthat are later used to make aluminum. The conversion of alumina toaluminum metal by electrolysis results in the substantial consumption ofcarbon anodes. Molten aluminum is deposited onto a carbon cathode andsimultaneously oxygen is deposited on and consumes the carbon anode ofthe electrolytic cell. Typically, up to 0.4 tonnes of carbon areconsumed for every tonne of aluminum produced. As a result, aluminumsmelters have a requirement for a substantial and continuous supply ofcarbon electrodes. Smelters commonly manufacture carbon anodes on siteas an integral part of the aluminum production process.

The manufacture of carbon anodes for the aluminum manufacturing processincludes producing “green” anode blocks and baking the “green” blocks toproduce anodes suitable for use in the aluminum manufacturing process.The production of “green” blocks involves the mixing of crushed coke oranthracite with a binding agent which, for example, contains coal tarpitch. The viscous mixture is then pressed to form “green” anode blocks.Depending on the smelter's requirements, “green” anodes may typicallyweigh from a few hundred kilograms to more than a tonne. The mixture ofcoke and pitch binder is generally solid at room temperature and softensat temperatures over about 50 degrees C. Volatile components arereleased at temperatures between 50 degrees C. and 400 degrees C. Whensubjected to further heating over a period of time, to about 1200degrees C., the anode hardens, resulting in improved physicalproperties, such as electrical conductivity and resistance to oxidation.

A carbon anode baking furnace having a substantially vertical bakingpath is disclosed in U.S. Pat. No. 7,086,856 which is incorporatedherein by reference. Green anodes are packed in sacrificial media withinthe vertical baking path and moved down through a baking zone. The bakedanodes are removed from the bottom of the baking path along with aportion of the sacrificial medium that surrounds the anodes. Themovement of the sacrificial medium within the baking path must becontrolled such that the removal of the bottom anode does not upset thepacking of the sacrificial medium about an anode disposed higher up thebaking path.

Another issue with the vertical-path furnace such as that disclosed inU.S. Pat. No. 7,086,856 is the removal of the baked anodes at the bottomof the furnace. The anodes are disposed in a self-supporting columnwhile in the baking path. The problem of removing the lowermost bakedanode while not upsetting the column is an issue desirous ofimprovement.

SUMMARY OF THE DISCLOSURE

The disclosure provides a carbon baking furnace having at least onevertical baking shaft with a system and method for positioning greencarbon bodies to be baked at the tops of the vertical baking paths andringing the green carbon bodies with a sacrificial medium such aspacking coke.

The disclosure provides a carbon baking furnace having at least onevertical baking shaft with a system and method for controlling thesacrificial medium used to surround the carbon bodies within the bakingpaths. The system and method includes elements disposed at the top ofthe furnace where the sacrificial medium is loaded and elements disposedat the bottom of the furnace where the sacrificial medium is unloaded.

The disclosure provides a carbon baking furnace having a system andmethod for unloading baked carbon bodies at the bottom of an array ofbaking paths while supporting the column of carbon bodies remaining inthe baking path.

The disclosure provides a volatile extraction system that extractsvolatile fumes from the upper portion of the furnace and introduces thevolatile fumes to the burners in the baking portion of the furnace. Thissystem allows the volatile fumes to be selectively directed to anafterburner and automatically delivered to the afterburner during anemergency.

The disclosure will now be further described with reference to theaccompanying drawings. In the drawings the carbon articles arerepresented by anodes for use in the aluminum smelting industry. It willbe understood that the features of the present invention applies equallyto the baking of other carbon articles provided in block or granularform.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an exemplary configuration of a vertical-pathcarbon baking furnace having a plurality of baking paths arranged in anarray.

FIG. 2 is a top view of the exemplary furnace configuration of FIG. 1.

FIG. 3 is a perspective view of the top of the furnace showing sixanodes positioned at their uppermost position with three of the bakingpaths empty for purposes of showing the structures around the top of thebaking path. FIG. 3 also shows the system for loading sacrificial mediuminto the baking paths around the anodes.

FIG. 4 is a perspective view of the top of a baking path with the anoderemoved to show the anode guides, the brushes, and the sacrificialmedium conveyors. This view also shows openings in the refractory blockthat define the inlets to the volatile fume removal system.

FIG. 4A is a perspective view of a liner for a volatile fume extractionchannel.

FIG. 5 is a view similar to FIG. 4 with the refractory block removed.

FIG. 6 is a perspective view from inside the baking path looking up tothe top of the baking path with the refractory block removed forclarity.

FIG. 7 is a perspective view of the loading end of a conveyor used todeliver sacrificial medium to the top of the baking path around ananode.

FIG. 8 is a perspective view of the end of the conveyor of FIG. 7showing the adjustment mechanism for the drive chain.

FIG. 9 is a perspective view of the conveyor of FIGS. 7 and 8 showingthe brush and the delivery openings that allow the sacrificial medium toexit the conveyor into the baking path around the anode.

FIG. 10 is a top perspective view of a portion of the conveyor of FIGS.7 and 8 showing an idler roller and a paddle that is used to distributethe sacrificial medium along the length of the conveyor.

FIG. 11 is a perspective view showing the afterburner and the stack witha schematic interconnection between the two.

FIG. 12 is a perspective view of the side of the furnace showing theequipment used to extract the volatile fumes and direct them into themain furnace burners.

FIG. 13 is a perspective view of the side of the furnace showing themain furnace burners and the pipes used to deliver the volatile fumes.

FIG. 14 is an end view of a coke removal structure at the bottom of thebaking path that controls the removal of the sacrificial medium.

FIG. 14A is a cross section of the coke removal structure showing themovement of the sacrificial medium with schematic arrows.

FIG. 15 is a perspective view of the end of the structure shown in FIG.14.

FIG. 16 is a perspective view looking up into the bottom of the bottomof an anode baking path showing the location of the structure of FIG. 15and also showing the actuation mechanism.

FIG. 17 is a perspective view of the system used to unload the bakedanodes from the furnace.

FIG. 18 is a perspective view looking up into the bottom end of thebaking path showing the holding devices used to support the anode columnwhile the lowermost anode is removed from the furnace.

FIG. 19 is perspective view of an end wall of the furnace showing theend support for the mechanism of FIGS. 14 and 15.

FIG. 20 is a perspective view looking down through the bottom of abaking path with the refractory block removed for clarity.

FIG. 21 is a perspective view of a mechanism that unloads the lowermostbaked anode and controls the movement of the anodes through the bakingpath.

FIG. 22 is a perspective view of the mechanism of FIG. 21 with portionsremoved to show additional features.

FIG. 23 is a side perspective view showing the holding devices of FIG.18 engaged with the anode while the lowermost anode is removed.

FIG. 24 depicts the drive assembly for the grippers that hold the anodestack during the unloading of an anode.

FIG. 25 depicts a pair of grippers disposed on a common drive shaft.

FIG. 26 is a perspective view of six volatile extraction channels shownwithout the refractory brick.

Similar numbers refer to similar parts throughout the specification.

DETAILED DESCRIPTION OF THE DISCLOSURE

An exemplary configuration of the vertical-path baking furnace isidentified by reference numeral 10 in the following description. FIG. 1depicts a front view of furnace 10 while FIG. 2 depicts a top view offurnace 10 showing the location of a plurality of carbon body bakingpaths 12 arranged in a three-by-four array with three baking path rowsand four baking path columns. The array of baking paths 12 thus includesa plurality (in this example ten) of perimeter baking paths that are notentirely surrounded by other baking paths and, in this example, aplurality (two) of captured baking paths 12 that are entirely surrounded(when viewed from the top) by other baking paths 12. The array of bakingpaths includes a front row 14 of baking paths 12, a middle row 16, and aback row 18. In other array configurations, there will be a differentnumber of middle rows 16. The front row is the closest to the unloadingdirection at the bottom of furnace 10. In FIG. 2, the baked carbonbodies are unloaded from the bottom of the baking paths 12 in thedirection that faces the bottom of the drawing page which corresponds tothe direction toward the viewer in FIG. 1 (this is the front 20 offurnace 10).

Green carbon bodies 30 are loaded into baking paths 12 at the top offurnace 10 and unloaded at the bottom of furnace 10 where the bakedcarbon bodies 30 are unloaded from a bottom of a baking path 12. Theunloading process controls the downward movement of the carbon bodies 30through furnace 10 during the baking process such that each verticalcolumn 32 of carbon bodies 30 is supported from the bottom. Carbonbodies 30 move through furnace 10 in a substantially continuous mannerand the time for a single carbon body 30 to move through baking path 12is many hours. It will be understood that the term “substantiallycontinuously” refers to a continuous mode of operation whereby carbonbodies 30 are moved in either a uniform rate or a periodic or step-wisepassage through furnace 10. Carbon bodies 30 are moved “substantiallycontinuously” through the baking process without the need for furnace 10to be shut down and cooled as in prior art in-ground anode bakingfurnaces. The substantially continuous movement includes the periodicstopping of the downward movement of column 32 that is required tounload the lowermost carbon body 30 from baking path 12.

The following exemplary configuration of furnace 10 is described as ananode baking furnace. Other carbon articles may be baked in this type offurnace and the inventions described herein are not to be limited toanodes used for aluminum production. Furnace 10 may be used with otherblock-like carbon articles or loose granular carbon articles.

The exemplary carbon baking furnace 10 shown in FIGS. 1 and 2 defines aplurality (twelve in this example) vertical baking paths 12. Paths 12are defined by a plurality of interlocking refractory blocks and otherrefractory materials 40 that are partially supported by an externalsupport frame 42 that is disposed below and around refractory block 40.Refractory block 40 defines baking paths 12, a plurality of fumechannels for hot baking gas flow, and a plurality of volatile fumechannels (inlets 44 seen in FIG. 4) for removing volatiles from furnace10 upon the initial heating of green anodes 30. These volatile fumechannels may be lined with a removable liner 45 shown in FIG. 4A. Liner45 defines a plurality of inlet slits 47 that are aligned with inlets 44when liner 45 is installed. Liner 45 also includes an end flange thatabuts the exterior of the blocks to position liner as shown in FIG. 12Frame 42 includes a plurality of lower supports 46 that supportrefractory block 40 above the floor 48 on which furnace 10 is supported.Lower supports 46 provide space for the unloading of the baked anodes30.

As the carbon anodes 30 pass through furnace 10, they are loaded at aloading zone at the top of furnace 10 and then pass down through avolatile extraction zone. Volatiles such as pitch fumes are extractedthrough holes or inlets 44 in the refractory materials 40 and are movedin the manner described below. Anodes 30 then pass through a baking orkiln area where the anodes baked at high temperatures and then to theunloading zone.

Green anodes 30 are positioned at the top of baking paths 12 with adelivery device 50 which may be in the form of the crane 50 depicted inthe drawings. Crane 50 supports anode 30 from its center (at depressionsdefined by the top of the anode) so that each anode 30 may be loweredinto baking path 12 without requiring supports disposed at the sides orunder article 30. If desired, this configuration allows crane 50 to loadanode 30 all the way to the bottom of baking path 12 when furnace 10 isinitially loaded. Anodes 30 also may be loaded from the bottom of eachcolumn. Further, this configuration allows crane 50 to reach into bakingpath 12 to remove anode 30 as needed. A spacer 52 may be positioned ontop of each anode 30. Spacer 52 may be fabricated from a refractorymaterial such as a ceramic. Spacer 52 may be provided in multiplesections that fit together on top of anode 30. The sections may overlapand have stepped edges of stepped joints to help spacer 52 fit together.

After a column is initially loaded and furnace 10 is fired and hasreached steady state, the anode column is slowly lowered in asubstantially continuous manner to bake the anodes. As the column islowered, a new green anode 30 is placed at the top of the column. Theinitial placement of anode 30 is such that anode 30 is disposedintermediate guides 60 of which at least one is disposed on each side ofthe top of baking path 12 such that anode 30 is centered above path 12.The initial location places the majority of the height of anode 30 abovethe top of baking path 12. As column 32 of anodes 30 is lowered throughpath 12, sacrificial medium such as granular packing coke is positionedaround anode 30 by a sacrificial medium delivery system 64.

In the exemplary configuration of furnace 10, anodes 30 are loaded intothe tops of the baking paths 12 with overhead crane 50 that lowers anode30 directly into the baking path 12. Crane 50 is capable of loweringanode 30 all the way to the bottom of each baking path 12 which is onemethod of initially loading furnace 10. Furnace 10 is initially loadedby creating columns 32 of anodes 30 surrounded by the packing material.The anode columns also may be created working from the bottom of furnaceby pushing successive greens anodes 30 up into the baking columns. FIG.2 depicts ten of the columns loaded (three with spacers 52 on top of theanode column 32) and two empty baking paths 12 waiting to be filled.After columns 32 of anodes 30 are established in each baking path 12,furnace 10 is started and brought up to its steady state operatingcondition and the anode columns 32 are lowered as described below. Whena column 32 is lowered to a level where the column 32 can accept thenext anode 30, the crane 50 is directed to pick up the next anode 30 anddeliver it directly on top of that column 32. Once anode 30 is inposition and crane 50 releases anode 30, the recesses in anode 30 usedby crane 50 are filled with packing material and then spacer 52 isplaced on top of anode 30. Spacers 52 may be supported by a secondswinging crane (not shown) during the process of positioning them forplacement.

Furnace 10 may include sensors that indicate the position of the top ofthe anode columns. The position of the anode column also may bemonitored by the removal of the lower baked anodes. Crane 50 maycommunicate with these sensors to trigger the pick up and delivery ofthe next anode to be loaded.

The next anode 30 is positioned directly on top of the anode column 32by a plurality of upper guides 60 shown in FIGS. 4 and 5. Upper guides60 are passive. Each upper guide 60 is mounted on a guide base 70 andincludes an arm 72 that is cantilevered from guide base 70. A curvedguide foot 74 is carried by the distal end of arm 72 in a position suchthat the straight bottom of guide foot 74 is substantially vertical anddisposed tangential to a portion of the anode column 32. The top ofguide foot 74 is curved or angled back toward guide base 70 (away fromits anode column 32) so that an anode 30 being lowered through guides 60will be guided into the correct position by the upper curved portion ofguide foot 74 in the situation where anode 30 is not perfectly alignedwith anode column 32 by crane 50 or when the dimensions of anode 30 areslightly out of spec. A pair of conical springs 76 are positionedagainst each other and between guide foot 74 and arm 72 to allow theposition of guide foot 74 to automatically adjust. In the exemplaryconfiguration, guide foot 74 is connected to arm 72 with a pair of bolts78 and conical springs 76 are carried on bolts 78 disposed between arm72 and guide foot 74.

A flexible seal 80 defined by a plurality of overlapping brushes 82having metal bristles is positioned at the upper end of each baking path12. The overlapping portions of brushes 82 at their corners may benotched as shown in FIG. 6. Seal 80 engages the perimeter of anode 30 asanode 30 drops down through seal 80. Seal 80 is disposed over the top ofthe sacrificial medium and limits migration of air into the sacrificialmedium.

Each section of seal 80 includes a plurality of metal bristles mountedin a U-channel 84 that is clamped between an L-shaped base mount 86 anda mounting strip 88 positioned over U-channel 84. This configuration isdepicted in FIGS. 9 and 10.

Furnace 10 includes an overall sacrificial medium delivery system thatgenerally includes at least one sacrificial medium storage container andat least one sacrificial medium conveyor that delivers sacrificialmedium from the container to the space around the top of anode column32. In the exemplary configuration of furnace 10, one sacrificial mediumconveyer assembly 64 is disposed on each side of each row of anodes 30such that there are six sacrificial medium conveyors 64 in thisexemplary configuration. Each of the six sacrificial medium conveyors 64is fed by its own sacrificial medium hopper 90. Each sacrificial mediumhopper 90 is filled automatically by a supplier conveyor (not shown) ormanually by the person overseeing the operation of furnace 10.

Each sacrificial medium conveyor 64 includes an elongated channel 92 anda sacrificial medium dispersement apparatus. Channel 92 is loaded withsacrificial medium from hopper 90 at its upstream end where thedispersement apparatus moves sacrificial medium downstream throughchannel 92. The loading may be a gravity feed. Apparatus 94 includes amotor 96 that drives a belt 98 having paddles 100 disposed withinchannel 92. Paddles 100 push the sacrificial medium in the downstreamdirection past a plurality of outlets 102 defined by the inner wall ofchannel 92 disposed adjacent anode column 32. Outlets 102 are disposedunder seal 80.

Hoppers 90 are held in place with a plurality of spaced U-bolts as shownin FIG. 7. The outlet of hopper 90 is disposed below belt 98. Thisconfiguration allows each hopper 90 to be readily removed if necessary.Belt 98 is supported on a drive gear 104 (FIG. 7), and end idler gear106 (FIG. 8), and at least one intermediate idler gear 108 (FIG. 10).Additional intermediate idler gears 108 may be provided as needed toavoid belt sag. End idler gear 106 is supported on tension bracket 110movable by turning tension bolt 112. Paddles 100 are L-shaped sectionsof metal bolted to belt 98.

Outlets 102 are elongated and spaced apart. A plurality of outlets 102have a length that is roughly four or more times as long as the heightof outlet 102. The height is large enough to accommodate the largestsize of sacrificial medium and the large width minimizes clogged outlets102 while also allowing for uniform distribution of sacrificial mediumalong anodes 30. As shown in FIG. 6, an outlet 102 is disposed at thecorner of anode 30 so that sacrificial medium is distributed to the endsof anodes 30 where the sacrificial medium fills in the ends by way ofgravity at the angle of repose for the sacrificial medium. Openings 102at corners may be larger than the other openings to promote thedistribution of sacrificial medium in these locations.

Nitrogen gas may be introduced into channels 92 such that the nitrogenwill migrate down into sacrificial medium around anodes 30. Flooding thesacrificial medium with nitrogen limits the amount of oxygen surroundinganode column 32 and thus limits any combustion within the sacrificialmedium. A fire suppression system also may be integrated into or justbelow channels 92 to flood the areas around the anode column with a firesuppressant.

The sacrificial medium moves down through baking path 12 with anodes 30and accommodates the movement and size changes of anodes 30 during thebaking process. The sacrificial medium may move at a rate that isdifferent from anodes 30. A lower seal 120 shown in FIGS. 14, 15 and 20supports the sacrificial medium and also limits migration of air intothe bottom of the sacrificial medium. Lower seal 120 is similar to upperseal 80 in that it includes overlapped brushes 82 with metal bristles.In the exemplary configuration, a plurality of stacked brushes 82 areused to form seal 120. The ends of the brush bristles are clamped in aU-channel 84 that is received directly in a slot defined by an innerwall 122 of a sacrificial medium removal channel 124. In the same manneras with channels 92, there is one removal channel 124 disposed alongeach side of each row of baking paths 12. In the exemplaryconfiguration, there are thus six removal channels 124.

The sacrificial medium is stopped by lower seal 120 and is moved overinner wall 122 into channel 124 between inner wall 122, an outer wall126, and a bottom wall 128 which define the upper portion of channel124. Bottom wall 128 of channel 124 defines openings which allow thesacrificial medium to drop down into an elongated inlet 130 to asacrificial medium control mechanism 132 which functions as anintermediate channel portion of removal channel 124. Mechanism 132controls the movement of sacrificial medium by removing the sacrificialmedium only as needed by automatically removing the sacrificial mediumfrom the top of a control channel 134. The top of control channel 134 ispositioned above the bottom of elongated inlet 130 such that sacrificialmedium must move upwardly before dropping onto an angled wall 135 of alower gathering channel portion of removal channel 124. The gatheredsacrificial medium is then removed to by way of a chute assembly 136into a collection hopper or is removed by chute assembly 136 to aconveyor that delivers sacrificial medium back to hoppers 90.

Control channel 134 catches the sacrificial medium and prevents it fromsimply falling out of furnace 10 by changing the flow direction of thesacrificial medium. In order to control the movement, control channel134 rocks back and forth on a pivot 138 about which its end panels 140are mounted. The rocking movement pushes the top portions of thesacrificial medium resting in control channel 134 over its edges intothe gathering channel portion below. The material is pushed by the lowerportions of elongated inlet 130 as channel 134 rocks back and forth asindicated by reference arrow 142 in FIG. 14A. The other arrows in FIG.14A depict the movement of the sacrificial medium. Control channel 134is driven back and forth by a drive mechanism 144 (schematically shownin FIG. 16) which is connected to each of removal channels 124 bylinking rods 146. Drive mechanism 144 rod 146 back and forth to rockeach of control channels 134. In the exemplary configuration, drivemechanism 144 is a cylinder that drives rod 146A back and forth belowthe metal beams that support refractory block 40. A slot 148 may bedefined in lower support 46 to accommodate rod 146A (see FIG. 16). Driverod extensions 146B are connected to drive rod 146A and to channel 134(or to tabs that extend down from channel 134 as shown in FIG. 26).Drive rod extensions 1468 transfer to movement of drive rod 146A tocontrol channel 134. Channels 134 may be rocked with their ownindividual actuators.

Intermediate guides 160 are disposed above seal 120 to ensure anodecolumn 32 is properly positioned for removal from furnace 10.Intermediate guides 160 have a similar structure as upper guides 60 andthe same reference numerals are used to identify these elements ofguides 160. The arms 72 of intermediate guides 160 extend down intosacrificial medium removal channel 124 and may abut bottom wall 128 ofchannel 124.

Chute assembly 136 moves the sacrificial medium out of furnace 10 to alocation where it can be screened and recycled. Chute assembly 136includes a plurality of lateral funnels 162 and a plurality of cornerfunnels 164.

Lower guides 180 are disposed below seal 120 and position anode 30 to beheld by the holding mechanism 182 that supports anode column 32 in placewhile the lowermost anode 30 is removed from furnace 10. Lower guides180 have a similar structure as upper guides 60 and the same referencenumerals are used to identify these elements of guides 180.

The holding mechanism includes a plurality of curved, toothed holdinggrippers 190 mounted to a rotatable drive shaft 192 that is rotated by adrive assembly 194. Drive assembly 194 rotates shaft 192 and thus pivotsgrippers 190 between engaged and disengaged positioned. When thelowermost anode 30 is ready to be removed from column 32, drive assembly194 is actuated to pivot grippers 190 into engagement with the side ofanode 30 as shown in FIG. 23. As the lowermost anode 30 is moved down,the next highest anode 30 starts moving down under the weight of column32 causing grippers 190 to bite into the side of that anode 30 untilgrippers 190 pinch that anode to a standstill. Column 32 thus stopsmoving and the lowermost anode is removed as described below.

An example of a drive assembly 194 is depicted in FIG. 24 whereincylinders 196 drive lever arms 198 that, in turn, rotate drive shafts192. This arrangement allows all of the grippers 190 to be controlledfrom the outer ends of furnace by extending shafts 192 out to thefurnace ends and locating cylinders 196 in these locations.

The downward movement of anode column 32 is controlled by the movementof a screw jack 200 positioned directly under column 32. Screw jack 200is configured to move slowly such as when it is being used to drop anodecolumn 32 down along baking path 12 during the baking of anodes 30.Screw jack 200 can also move relatively fast such as when it is removingthe lowermost anode 30 from furnace 10. Screw jack 200 maintains itsslow movement until grippers 190 are holding column 32. Screw jack 20then changes to its faster movement and lower the lowermost anode 30down to a gravity powered passive conveyor 202 which removes the anodeto a removal area 203 (FIG. 17) where a forklift can remove the bakedanodes.

During this process, the anode 30 from the front row 14 of the bakingpath array is removed first and the screw jack 200 remains retracteddown under the conveyor 202 until the anodes from the middle 16 row isremoved and, following the same process, the anode from the back row 18is removed. In an alternate configuration, the back row anode may beremoved from the back of the furnace. This process allows the anodesfrom the middle and back rows to slide down conveyors 202 without beingstopped by the jack screws for the front row of anodes. After anodes 30are removed from all rows 14, 16, and 18, screw jacks 200 are extendedback up to engage columns 32. In order to break the grip of grippers190, screw jacks 200 lift column 32 up until grippers 190 release or aredriven back to their disengaged positions. At that time, screw jack 200starts moving column 32 downward again until the new lowermost anode 30is ready for removal. This process may be reserved to initially loadfurnace 10. If loaded from the bottom, screw jack 200 lifts an anode 30to grippers 190 where it is held until pushed up by the next anode 30being loaded.

As shown in FIGS. 21 and 22, screw jack 200 extends through the centerof conveyor 202. An engagement plate 204 is carried at the top of screwjack 200 to engage anode 30. Plate 204 is supported at five locationsincluding the powered central screw 206 and four corner guides 208.

As described above, furnace 10 has a volatile extraction zone whereanodes 30 are initially heated and volatiles are driven off intoextraction channels 45 such as the one depicted in FIG. 4A. FIG. 26shows the arrangement of six channels 45 and their communication with avolatile extraction main duct 210. Duct 210 delivers volatiles to theburners 211 as shown in FIG. 13 when a first gate valve 212 is open anda second valve 214 (at the top of duct 210) is closed. Gate valves 212and 214 are controllable to deliver the volatile fume to either burner211 or to an afterburner 216 (FIG. 11). Each gate valve 212 and 214 hasits own actuator to allow the valve to be automatically controlled. Whenfirst gate valve 212 is closed and second gate valve 214 is open,volatile fume is delivered to afterburner and this configuration isautomatically actuated during an emergency situation or when burners 211are off. Afterburner 216 exhausts to stack 218 for delivery to theatmosphere or to further environmental controls.

Burners 211 and the air delivery ducts are mounted to accommodateexpansion and contraction of the refractory blocks of furnace 10. FIG.13 shows each burner 211 mounted to a plenum 220 that accommodatesmovement of the refractory block. A plurality of springs 222 are usedbetween the components and frame 42 to create a holding force againstthe block while allowing for accommodation of block movement. The airdelivery system uses similar springs and adjustable plenums toaccommodate movement.

In the foregoing description, certain terms have been used for brevity,clearness, and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes and are intended to be broadlyconstrued. Moreover, the description and illustration of the furnace isan example and the furnace is not limited to the exact details shown ordescribed. Throughout the description and claims of this specificationthe words “comprise” and “include” as well as variations of those words,such as “comprises,” “includes,” “comprising,” and “including” are notintended to exclude additives, components, integers, or steps.

1. A vertical path carbon baking furnace for baking green carbonarticles; the furnace comprising: a furnace body defining asubstantially vertical baking path adapted to receive the carbonarticle; the vertical baking path having a volatile extraction zonedisposed above a baking zone; the furnace body defining a volatileextraction inlet in communication with the baking path; the volatileextraction inlet being disposed in the volatile extraction zone of thebaking path; the furnace body defining baking fume channels disposed onopposite sides of the baking path to receive baking fumes; a burnerassociated with each the baking fume channel; and the volatileextraction inlet in fluid communication with a burner such that volatilefumes extracted from the baking path through the volatile extractioninlet are delivered to the burner for combustion.
 2. A vertical pathcarbon baking furnace for baking green carbon articles; the furnacecomprising: a furnace body defining a substantially vertical baking pathadapted to receive the carbon article; the baking path having upper andlower ends; a sacrificial medium delivery system disposed at the top ofthe baking path; the sacrificial medium delivery system including a pairof channels disposed on opposite sides of the baking path; each of thechannels defining outlets adapted to deliver sacrificial medium from thechannel to the baking path; and a sacrificial medium conveyor disposedin the channels; the conveyor having movable elements that deliversacrificial medium to the channel outlets along the length of thechannels.
 3. A vertical path carbon baking furnace for baking greencarbon articles; the furnace comprising: a furnace body defining asubstantially vertical baking path adapted to receive the carbonarticles in a stacked column wherein the stacked column has a lowermostarticle and a second lowermost article; the baking path having upper andlower ends; an unloading device disposed under the baking path tocontrol the movement of the column through the baking path; a holdingmechanism associated with the baking path; the holding mechanism havingelements that selectively support the second lowermost articleindependent of the lowermost article; and the holding mechanismincluding a plurality of grabs that selectively rotate downwardly andinwardly relative to the article from a disengaged position to anengaged position; the plurality of grabs including grabs disposed onopposite sides of the article such that the weight of the article causesthe article to be pinched and held by the opposed grabs.